In this review, the use of the most common selection marker genes on plant transformation and the effects of their respective selective agents are discussed. These genes could be divided in two categories according their mode of action: genes for positive and negative selection. The retention of the marker gene flow through chloroplast transformation is also discussed. Further, strategies to recover marker-free transgenic plants, involving multi-auto-transformation (MAT), co-transformation, site-specific recombination and intragenomic relocation of transgenes through transposable elements are reviewed.

Jatropha curcas L. is a versatile crop since all its plant material is brought to use either as energy source, industrial or medicinal purpose. Several studies are ongoing in different parts of the world to optimize, enhance and exploit the growth, fruiting cycle and different developmental stages of the plant so that the economic yield of the plants can be utilized to the fullest limits. Foliar application of plant growth regulators such as ethrel (an ethylene releasing compound), indole acetic acid (IAA) and naphthalene acetic acid (NAA) at 50, 100 and 150 ppm, was found to influence different morpho-physiological characters in Jatropha curcas L, such as plant height, collar diameter, tree spread, flower initiation, number of inflorescence per plant, number of male and female flowers per inflorescence, and the ratio of male: female flowers per inflorescence. Moreover, the leaves chlorophyll content, Fv/Fm value, nitrate reductase activity and proline content were also affected by synergistic response of auxin and ethylene. As higher the plant growth regulators concentration higher was the synergic effect on the Jatropha curcas L physiology.

Since the beginning of Human civilization, the soil organic matter has been used as plant growth promoter and/or regulator. Indeed, early in plant science history, even before the auxin concept has been established, the term "auximones" was coined to describe plant growth promoting humic acids derived from peat. Despite of this, until the end of the 20th century, humic substances remained as some of the most neglected environment signals in plant physiology research. However, this scenario has changed in last decade with the discovery that the major systems of energy transduction of the plant cell membranes, the proton pumps, can be tightly orchestrated by humic substances just as elicited by a hormonal signaling. Differential activations of both plasma membrane (PM H+-ATPase) and vacuolar pumps (V-ATPase and H+-PPase) are modulated by humic substances triggering ion signatures related to specific patterns of plant growth and development. Phytohormones have been found to be associated with this humus bioactivity, and nitric oxide acting as a second messenger in a signaling pathway in which plants can sense the soil environment to cope with specific conditions. In this review, we discuss some of the most influential data available in literature...

We used
Computer-Assisted Personalized Approach (CAPA), a networked teaching
and learning tool that generates computer individualized homework
problem sets, in our large-enrollment introductory plant physiology
course. We saw significant improvement in student examination
performance with regular homework assignments, with CAPA being an
effective and efficient substitute for hand-graded homework. Using
CAPA, each student received a printed set of similar but individualized
problems of a conceptual (qualitative) and/or quantitative nature with
quality graphics. Because each set of problems is unique, students were
encouraged to work together to clarify concepts but were required to do
their own work for credit. Students could enter answers multiple times
without penalty, and they were able to obtain immediate feedback and
hints until the due date. These features increased student time on
task, allowing higher course standards and student achievement in a
diverse student population. CAPA handles routine tasks such as grading,
recording, summarizing, and posting grades. In anonymous surveys,
students indicated an overwhelming preference for homework in CAPA
format, citing several features such as immediate feedback, multiple
tries...

Microarrays have become an important technology for the global analysis of gene expression in humans, animals, plants, and microbes. Implemented in the context
of a well-designed experiment, cDNA and oligonucleotide arrays can provide highthroughput,
simultaneous analysis of transcript abundance for hundreds, if not
thousands, of genes. However, despite widespread acceptance, the use of microarrays
as a tool to better understand processes of interest to the plant physiologist is still
being explored. To help illustrate current uses of microarrays in the plant sciences,
several case studies that we believe demonstrate the emerging application of gene
expression arrays in plant physiology were selected from among the many posters
and presentations at the 2003 Plant and Animal Genome XI Conference. Based
on this survey, microarrays are being used to assess gene expression in plants
exposed to the experimental manipulation of air temperature, soil water content and
aluminium concentration in the root zone. Analysis often includes characterizing
transcript profiles for multiple post-treatment sampling periods and categorizing
genes with common patterns of response using hierarchical clustering techniques.
In addition, microarrays are also providing insights into developmental changes
in gene expression associated with fibre and root elongation in cotton and maize...

Often, plant-pathogenic microbe interactions are discussed in a host-microbe two-component system, however very little is known about how the diversity of rhizospheric microbes that associate with plants affect host performance against pathogens. There are various studies, which specially direct the importance of induced systemic defense (ISR) response in plants interacting with beneficial rhizobacteria, yet we don’t know how rhizobacterial associations modulate plant physiology. In here, we highlight the many dimensions within which plant roots associate with beneficial microbes by regulating aboveground physiology. We review approaches to study the causes and consequences of plant root association with beneficial microbes on aboveground plant-pathogen interactions. The review provides the foundations for future investigations into the impact of the root beneficial microbial associations on plant performance and innate defense responses.

All eukaryotes contain sterols, which serve as structural components in cell membranes, and as precursors for important hormones. Plant vegetative tissues are known to contain mixtures of sterols, but very little is known about the sterol composition of phloem. Plants are food for many animals, but plant-feeding arthropods (including phloem-feeding insets) are unique among animals in that they have lost the ability to synthesize sterols, and must therefore acquire these essential nutrients from their food, or via endosymbionts. Our paper starts by providing a very brief overview of variation in plant sterol content, and how different sterols can affect insect herbivores, including those specializing on phloem. We then describe an experiment, where we bulk collected phloem sap exudate from bean and tobacco, and analyzed its sterol content. This approach revealed two significant observations concerning phloem sterols. First, the phloem exudate from each plant was found to contain sterols in three different fractions – free sterols, sterols conjugated to lipids (acylated), and sterols conjugated to carbohydrates (glycosylated). Second, for both plants, cholesterol was identified as the dominant sterol in each phloem exudate fraction; the remaining sterols in each fraction were a mixture of common phytosterols. We discuss our phloem exudate sterol profiles in a plant physiology/biochemistry context...

Increased expression of the aquaporin NtAQP1, which is known to function as a plasmalemma channel for CO2 and water, increases the rate of both photosynthesis and transpiration. In contrast, increased expression of Arabidopsis hexokinase1 (AtHXK1), a dual-function enzyme that mediates sugar sensing, decreases the expression of photosynthetic genes and the rate of transpiration and inhibits growth. Here, we show that AtHXK1 also decreases root and stem hydraulic conductivity and leaf mesophyll CO2 conductance (gm). Due to their opposite effects on plant development and physiology, we examined the relationship between NtAQP1 and AtHXK1 at the whole-plant level using transgenic tomato plants expressing both genes simultaneously. NtAQP1 significantly improved growth and increased the transpiration rates of AtHXK1-expressing plants. Reciprocal grafting experiments indicated that this complementation occurs when both genes are expressed simultaneously in the shoot. Yet, NtAQP1 had only a marginal effect on the hydraulic conductivity of the double-transgenic plants, suggesting that the complementary effect of NtAQP1 is unrelated to shoot water transport. Rather, NtAQP1 significantly increased leaf mesophyll CO2 conductance and enhanced the rate of photosynthesis...

In this review we discuss some of the most influential data available in literature, which have shaped this underexplored interface between the chemistry of the organic matter and the plant physiology.; 2013; Titulo anterior: Brazilian Journal of Plant Physiology

The thesis was divided in four articles, in which three are related to
in vitro propagation and how the microenvironmental conditions play on
physiology and anatomy of B. zebrina. The last article is related to
anatomical and physiological changes of B. zebrina under copper (Cu)
excess stress. For all studies, B. zebrina plants were previously in vitroestablished in MS medium. Plants were transferred to media at
concentrations of 0%, 50%, 100%, 150% or 200% of the original salt
concentration of MS medium. The media were prepared in two different
consistencies, stationary liquid and 6 g L-1 agar. For in vitro rooting studies,
the shoots grew in a medium supplemented with different sucrose
concentrations. Soluble carbohydrates contents were assessed after the
rooting. The in vitro multiplication of B. zebrina shoots is enhanced by using
200% of MS-salts concentration and liquid medium. The use of 15 g L-1
sucrose increased endogenous carbohydrate stocks and induced a good
formation of the root systems on in vitro shoots. From these results, a second
experiment was designed. B. zebrina side shoots were transferred to culture
media containing 0.0, 15.0, 30.0, 45.0 or 60.0 g L-1 sucrose. Two different
culture container sealing systems were tested: lids with a filter and a filter
covered with PVC. At 45 days in vitro growth...

Waterlogging has been reported to reduce crop yields by up to 80 %, although the lack of a consistent definition of waterlogging or specific effects on plants makes it hard to accurately ascribe crop yield losses to waterlogging relative to other abiotic stresses. After reviewing the available literature I suggest that recording soil profile information, topographic data, meteorological information, plant morphological appearance and areas with visible surface water are the most important factors for describing waterlogging in the field. An above ground plant response to waterlogging that is easily identifiable in some species is leaf wilting. Reduced root hydraulic conductance was investigated as the possible cause of leaf wilting by waterlogging Glycine max L. and Nicotiana glutinosa L. under greenhouse conditions. During these experiments a defined sequence of plant responses and adaptations to waterlogging was established. Waterlogged soybean showed very little change in plant physiology or morphology implying a low sensitivity to reduced root zone soil oxygen concentration [O₂]. At the other end of the waterlogging sensitivity scale before [O₂] reached 10 % there was a 50 % reduction in root dry weight of N. glutinosa on day 2 of waterlogging. On day 3 of waterlogging there was decreased stomatal conductance and leaf water potential...

The effects of NaCl salinity on seed germination, growth, physiology, and biochemistry of two bambara groundnut landraces (Vigna subterranea (L.) Verdc), Kakamega (white seed coat) and Mumias (red seed coat), were investigated with the aim of establishing traits, which can provide a basis for breeding to salt tolerance in groundnuts. A study was conducted under laboratorial and greenhouse conditions. Bambara groundnut seeds and plants were subjected to five concentrations of NaCl solutions with several electrical conductivities: 0 (control), 6.96, 12.93, 19.89, and 25.86 dS m-1. Germination percentage, growth, chlorophyll fluorescence, and leaf chlorophyll content were determined. Sodium chloride salinity (p<0.05) significantly decreased germination and plant growth in both landraces. Mumias had significantly higher total chlorophyll, chlorophyll a and b content compared to Kakamega landrace. Salinity significantly decreased Fv/Fm ratio and electron transport rate in the two landraces, however there were no significant (p>0.05) differences in the Fv/Fm values for Mumias' landrace, as compared to the Control. Overall, Mumias' landrace seeds seemed to be more salt-tolerant at higher salinity levels compared to Kakamega. A greater reduction in growth in Mumias than in Kakamega is a possible indicator for salt tolerance. The chlorophyll fluorescence parameters may not be used to identify salt sensitivity between the two landraces. The results indicated that leaf area and seed germination were suitable parameters for screening the two bambara landraces for salt tolerance.

Human beings enjoy the flavor and stimulating activity of a cup of coffee without knowing that by doing so, they are part of a 'food web' and receive signals coffee plants build to improve their struggle for life. This review is centered in the first part on the purine alkaloid caffeine and its physiological role in the coffee plant's life cycle. Many of the thoughts and ideas presented here are plain speculation, because the real research revealing the secrets of plant physiology such as e.g. the formation of the coffee bean with all its ingredients, has just started. The recent achievements in molecular biology made it possible to tackle and answer new questions regarding the regulation of secondary metabolism in the coffee plant organs at selected stages of their development. Brazilian research groups have much contributed to the recent progress in molecular biology and physiology of coffee. Among them was Maro R. Söndahl, in commemoration of whom this article has been written. Thus, the second part reports on the very first steps Maro and I made together into a very new field of coffee, that is metabolite profiling. The outcome was amazing and gives an idea of the great potential of this technique to map in future the complex network of the coffee metabolom.

Agricultural research and development plays an essential role in a nation's economic development, providing for food security for an ever-increasing population. In developed countries, the gap between potential and actual yield is largely closed because of a combination of advanced technologies, high-yielding new varieties and the application of agrochemicals in highly mechanized production systems. In most of these countries, agricultural production exceeds national demand, resulting in excess products for export. In many of the developing countries, however, agricultural productivity is still far below what it should be because of multiple technical and socio-economic constraints. Food deficits are the norm in poor and middle-income countries, requiring expensive food imports. To partially alleviate this situation, agricultural research must be strengthened. As branches of basic sciences, plant and crop physiology have often been criticized for being non-effective in translating their findings into improving crop productivity, which would enhance agricultural progress. This paper addresses this issue by presenting an assessment of past achievements of physiological research and their impacts on crop improvement and food production. Shortcomings and limitations of isolated...

Plants respond to changes in their local environment and, at the same time, influence the environment at a global scale. The molecular and physiological mechanisms regulating this interaction are not completely understood and this limits our capacity to predict the response of vegetation to future environmental changes. This dissertation combined tools from genomics, physiology, and ecology to examine the response of plants to environmental change. Specifically, it focused on processes affecting carbon and water exchange in forest trees because (1) trees are long-lived species that might face repeated environmental challenges; (2) relatively little information exists about the genes and the molecular mechanisms regulating structural and physiological traits in adult, long-lived woody plants; and (3) forest trees exchange a significant amount of carbon and water with the atmosphere and are therefore major players in the global carbon and water cycles.

Water flux through forests depends both on environmental conditions (e.g., soil moisture) and on the hydraulic architecture of individual trees. Resistance to xylem cavitation is an important hydraulic trait that is often associated with drought tolerance but potentially at the cost of reduced carbon uptake. The second chapter of this dissertation evaluated the variation in resistance to xylem cavitation...

This paper is a research and journalistic work that summarizes and synthesizes the scientific development of the physiology of plants in the American tropics, also known as the Neotropics. It contains the contributions of numerous biologists interested in the physiology of tropical plants. The fabulous structural and functional diversity of tropical forests is still the major driver of research in this field. Classical physiological work involving tropical plants, such as the discovery of C4 photosynthesis in sugarcane, is invoked to exemplify the historical and current importance of physiological research in the tropics, and its applications in agriculture, forestry and conservation. An historical background describing the early and more recent development of a tradition on the physiological study of tropical plants is followed by a summary of the research conducted on the physiology of tropical crops. Common areas of interest and influence between the fields of crop physiology and plant ecophysiology are identified and exemplified with problems on the environmental physiology of crops like coffee and cassava. The physiology of tropical forest plants is discussed in terms of its contributions to general plant physiological knowledge in areas such as photosynthetic metabolism and plant water relations. Despite the impressive technical advances achieved during the past decade...